N trifluoroacetate

TRIFLUOROACETYLATION OF AMINES AND AMINO ACIDS UNDER NEUTRAL, MILD CONDITIONS N-TRIFLUOROACET ANILIDE AND N-TRIFLUOROACETYL-l-TYROSINE... 

At about the same time, a synthesis of leukotriene-A, also termed SRS-A ( slow reacting substance of anaphylaxis ), which made use of the Wittig olefmation was described77). The ylide of 100 is reacted with ethyl 5-formyl-2,4-pentadienoate 101 to give the ( , , Z, Z)- tetraenoic ester 102. Reduction and mesylation of 102, subsequent conversion into the sulfonium salt, and treatment of the latter with a base yields a sulfonium ylide which is reacted with methyl 4-formylbutanoate 69 to the epoxy-tetraenoic ester 103. After separation of the cis-epoxide by HPLC, 103 was treated with the S-trimethylsilyl derivative of glutathione dimethyl ester N-trifluoroacet-amide. The diastereomeric products thus obtained were separated by means of HPLC and hydrolyzed to 104 77) (Scheme 18). 

During studies on the functionalization of the benzomorphan 2-position, Portoghese and co-workers 117,120) reported the preparation of a 4-cyanoben-zomorphan from the treatment of the corresponding N-trifluoroacetate with aqueous KCN. Another study 121,122) demonstrated that cyanation a- to nitrogen in benzomorphans bearing a 4-methyl group may be used to insert a second alkyl substituent in the 4-position. The nature of the cyanation product... 

Mercury(n) trifluoroacetate [13257-51-7] M 426.6, m 171-173". It is prepared from HgO and trifluoroacetic acid and is reciystallised from trifluoroacetic anhydride/trifluoroacetic acid. It is a useful reagent for mercuration of aromatic compounds [Lau Kochi J Am Chem Soc 108 6720 1986]. Store it in a tightly stoppered bottle away from light, [cf Aylett in Comprehensive Inorganic Chemistry (Bailer et al. eds) Vol 3 pl87 1973, Beilstein 2 IV 458.] It is veiy TOXIC and hygroscopic. 

Palladium(n) trifluoroacetate [42196-31-6] M 332.4, m 210"(dec). Suspend it in trifluoroacetic acid and evaporate it on a steam bath a couple of times. The residue is then dried in vacuum (40-80°) to give a brown powder. It is hygroscopic and should be stored in a dry atmosphere, preferably aliquoted in sealed vials [Stephenson et al. J Chem Soc 3632 1965, Trost Metzner Chem Soc 102 3572 1980.]... 

Ligand Replacement Unidentate by Unidentate.—Replacement of the hydroxo-ligand in [Co(salen)(OH)py] by malononitrile is thought to take place by nucleophilic substitution of the carbanion from malononitrile at the cobalt atom. Rate constants have been determined for the four-stage process by which the rhodium(n) acetate dimer is converted by reaction with trifluoroacetic acid into the rhodium(n) trifluoroacetate dimer. Rates have also been determined for the reaction of nitrato-zirconium(iv) species with bis-(2-ethylhexyl) hydrogen phosphate. ... 

Lithium tetrafluoroborate in wet acetonitrile has been described as an effective combination for the hydrolysis of acetals under mild weakly acidic conditions. Dithians were unaffected. Methods for the hydrolysis of thioacetals continue to appear. Reagents that have been described include a polystyryl-mercury(n) trifluoroacetate combination, which retains the metal on the resin, lead(iv) dioxide and boron trifluoride etherate, aqueous hydrochloric acid in dioxan containing dimethyl sulphoxide, methyl-bis(methylthio)sulphonium hexa-chloroantimonate, and iodoxybenzene, catalysed by toluene-p-sulphonic acid. Dithioacetals derived from ethane-1,2-dithiol may be cleaved with dimethyl sulphoxide in combination with either t-butyl or trimethylsilyl bromides and iodides. Regeneration of ketones from ethanediyl-S S -acetals via the lithium-di-isopropylamide-promoted fragmentation to the thioketone and subsequent hydrolytic work-up only gives satisfactory yields for aryl methylketone derivatives. Dithioacetal SS-dioxides are rapidly cleaved in hot methanolic hydrochloric acid solution. ... 

In each step of the usual C-to-N peptide synthesis the N-protecting group of the newly coupled amino acid must be selectively removed under conditions that leave all side-chain pro-teaing groups of the peptide intact. The most common protecting groups of side-chains (p. 229) are all stable towards 50% trifluoroacetic acid in dichloromethane, and this reagent is most commonly used for N -deprotection. Only /ert-butyl esters and carbamates ( = Boc) are solvolyzed in this mixture. 

A -(2 2-Diethoxyethyl)anilines are potential precursors of 2,3-unsubstituted indoles. A fair yield of 1-methylindole was obtained by cyclization of N-inethyl-M-(2,2-diethoxyethyl)aniline with BFj, but the procedure failed for indole itself[2], Nordlander and co-workers alkylated anilines with bromo-acetaldehyde diethyl acetal and then converted the products to N-trifliioro-acetyl derivatives[3]. These could be cyclized to l-(trifluoroacetyl)indoles in a mixture of trifluoroacetic acid and trifluoroacetic anhydride. Sundberg and... 

The most suitable synthetic method for these products is the heterocyc-lization reaction of N-thioacyl derivatives of amino acids (202) with phosphorus tribromide (378, 442-450, 559, 560) or anhydrous trifluoroacetic acid (448, 449, 451, 452) (Scheme 103). Treatment of N-thioacyl amino acids with acetic anhydride leads directly to the thiazolylacetate without isolation of an intermediate thiazolinone (365. 452). 2-Alkoxy-derivatives of A-2-thiazoline-5-one, however, can be obtained without acetylation by this method (453, 454). 

Methylammonium N Ethyl N methylcyclopentyl chlonde ammonium trifluoroacetate... 

Step n When the peptide is completely assembled it is removed from the resin by treatment with hydrogen bromide m trifluoroacetic acid... 

Nonvolatile analytes must be chemically converted to a volatile derivative before analysis. For example, amino acids are not sufficiently volatile to analyze directly by gas chromatography. Reacting an amino acid with 1-butanol and acetyl chloride produces an esterfied amino acid. Subsequent treatment with trifluoroacetic acid gives the amino acid s volatile N-trifluoroacetyl- -butyl ester derivative. 

Several electrophiles, such as acetic anhydride, nitric acid or alternative nitrating agents, such as ammonium nitrate in trifluoroacetic anhydride (41), or sodium hypochlorite, react at N-1, which is followed by reaction at N-3 under suitable conditions. In the case of acetic anhydride, the reaction can take place exclusively at N-3 if N-1 is hindered this fact has served as a criterion for studying the stereochemistry of 5-spirohydantoin derivatives (42,43). 

The need for pyrazoles substituted with the trifluoroacetyl group led to the reaction of ethoxyvinyl ether with trifluoroacetic anhydride, yielding 4-ethoxy-l,l,l-trifluoro-3-buten-2-one (38) this further reacted with aldehyde / fZ-butyUiydrazones, and after cyclization at room temperature under mildly acidic conditions the pyrazoles were obtained in satisfactory yields (eq. 7). Further treatment with H2SO4 removed the tert-huty group, thus providing an opportunity for further derivatization at N. ... 

Aqueous salt solutions such as saturated 2inc chloride [7646-85-7] or calcium thiocyanate [2092-16-2] can dissolve limited amounts of cellulose (87). Two non-aqueous salt solutions are ammonium thiocyanate [1762-95-4]— uoamonia. and lithium chloride /744Z-4/A/—dimethyl acetamide [127-19-5]. Solutions up to about 15% can be made with these solvents. Trifluoroacetic acid [76-05-17—methylene chloride [75-09-2] and /V-methy1morpho1ine N-oxide [7529-22-8]—(92—94) are two other solvent systems that have been studied (95). 

An aiyl 4-picolyl ether is stable to trifluoroacetic acid, used to cleave an N-t-butoxycarbonyl group. ... 

This thiourea, prepared from an amino acid and phenyl isothiocyanate, is cleaved by anhydrous trifluoroacetic acid (an N-COCF3 group is stable), and by oxidation (/72-CIC6H4CO3H, 0°, 1.5 h, 73% yield H2O2/ACOH, 80°, 80 min, 44% yield). ... 

Molecular bromine is believed to be the reactive brominating agent in uncatalyzed brominations. The brominations of benzene and toluene are first-order in both bromine and the aromatic substrate in trifluoroacetic acid solution, but the rate expressions become more complicated when these reactions take place in the presence of water. " The bromination of benzene in aqueous acetic acid exhibits a first-order dependence on bromine concentration when bromide ion is present. The observed rate is dependent on bromide ion concentration, decreasing with increasing bromide ion concentration. The detailed kinetics are consistent with a rate-determining formation of the n-complex when bromide ion concentration is low, but with a shift to reversible formation of the n-complex... 

N-chloroamine functionalization of the angular methyl group preparation of 3/3-hydroxy-18-chloro-20a-methylamino-5a-pregnan-l l-one trifluoroacetate, 259... 

Hydroxy-5 a-bromo-6ft 19-oxidoandro-stan-17-one acetate, 266 3iS-Hydroxy-N-chloro-20o -methylamino-5a-pregnan-l 1-one, 259 3 -Hydroxy-18-chloro-20a-methylamino-5o -pregnan-l 1-one trifluoroacetate, 259 3 -Hy droxy-17 a-chloropr egn- 5-en-20-one acetate, 349... 

Treatment of N hydroxysuccinimide with trifluoroacetic anhydnde gives N trifluoroacetoxysuccinimide quantitatively [27] Some otherwise hardly accessible trifluoroacetylated tertiary alcohols are readily prepared, though in poor yields, by reacting the appropriate anhydride with an excess of an organometallic reagent [22] (equation 11)... 

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